When a shuttle valve is used in a fluid system, the two inlet ports of the shuttle valve may be connected to different sources of fluid pressure. The different sources of fluid pressure may be at different pressure levels, and each of the pressure levels may increase or decrease with time. The shuttle closes fluid pressure communication between the lower pressure source inlet port and the outlet port. The shuttle also establishes and maintains fluid pressure communication between the higher pressure source inlet port and the outlet port. As used herein, the term fluid pressure communication with reference to two or more surfaces or volumes means that such surfaces or volumes are in relatively open fluid flow communication and/or at substantially similar pressure levels under normal operating conditions when such surfaces or volumes are in the described configuration. The terms inlet port or inlet and outlet port or outlet do not preclude fluid flow in a reverse direction such that an inlet becomes an outlet or an outlet becomes an inlet, unless the context otherwise so requires. The terms up, down, left and right are explanatory and do not preclude opposite sides or opposite directions, unless the context otherwise requires.
The shuttle, which may also be referred to as a valve member, may have a first at rest position and a second at rest position. In the first at rest position, the lower fluid pressure source may be connected to the first inlet port and the higher fluid pressure source may be connected to the second inlet port. In this configuration, a first valve surface of the poppet closes fluid pressure communication between the lower pressure source first inlet port and the outlet port while fluid pressure communication between the higher pressure source second inlet port and the outlet port is established and maintained. In the second at rest position, the relative pressure levels of the first and second inlet ports may reverse, so that the first inlet port may be at the higher pressure level and the second inlet port may be at the lower pressure level. In this configuration, a second valve surface of the shuttle poppet closes fluid pressure communication between the lower fluid pressure source second inlet port and the outlet port while fluid pressure communication between the higher fluid pressure source first inlet port and the outlet port is established and maintained. In this manner, the inlet port that is at the higher pressure level is connected to the outlet port.
The shuttle of the shuttle valve is moved between its first and second at rest positions in response to fluid pressure. More specifically, the shuttle is moved in response to the fluid pressure differential between the first inlet port and the second inlet port. Some shuttle valves may include biasing members to prevent movement of the shuttle poppet until a predetermined pressure differential between the inlet ports is reached. Additionally, shuttle valves may include cushioning devices to control the speed of movement of the shuttle.
Shuttle valves of this type may be used in any of several known applications. One such application is in drilling fields in which drilling rigs drill wells into the ground (including underwater surfaces) for locating and connecting to underground fluid resources such as oil or natural gas or for locating and connecting to underground chambers to pump fluids into the chambers for storage. In these uses, the shuttle valve may be used as a component in a blow out preventer circuit that is designed to change fluid flow paths and prevent or limit over pressure conditions that might blow out piping or other components during instances of rapid high pressure build up in the well. A blow out preventer is any fluid circuit that operates in any application to change the path of fluid flow in response to fluid pressure change. A drilling field blow out preventer is any such blow out preventer that is used in connection with well drilling into the ground.
In some cases, an application requires that two or more shuttle valves be sequenced together, such that the outlet port of one shuttle valve will be directed to an inlet port of the next shuttle valve. In these cases, the shuttle valves are made to stack one adjacent the other, with their housings held together as a unitary valve body assembly. The term unitary valve body assembly means of a multi-piece construction of more than one valve body, assembled such that the multiple valve bodies function as a single valve body without external fluid hoses or other external fluid pressure lines. The term unitary stacked shuttle valve body assembly means a unitary valve body assembly in which each of the valve bodies is a shuttle valve body secured to at least one adjacent shuttle valve body with the outlet of one shuttle valve being connected to the inlet of an adjacent shuttle valve.
When shuttle valves are stacked together, constraints including space constraints may limit how the assembly can be installed or connected or may make certain installation configurations more desirable than others. In certain known prior art unitary stacked shuttle valve body assemblies, the assembly has only a single fixed port configuration, and the installation must be arranged or modified in order to accommodate the fixed port configuration. For example, FIG. 12 of U.S. Pat. No. 6,257,268 B1 illustrates a prior art unitary stacked shuttle valve body assembly. The outlet ports of each of the shuttle valves of this prior art assembly become internal inlets to its adjacent shuttle valve. In this prior art assembly, a middle one of the shuttle valve bodies cannot be assembled in different positions relative to the other shuttle valve bodies in order to move the location of its external inlet port. Also, the illustrated internal and external inlet connections for each shuttle valve body in this prior art assembly cannot be interchanged to allow changing the external inlet from one side of the shuttle valve body to the other.